Blog

Today’s growing demands on IT infrastructure have two specific dimensions. The first is economic: How can we reduce the cost of transmitting data between data centers as business needs continue to grow? The second dimension concerns security: Will data transmitted today still be secure in a few years when quantum computers change the way we assess cryptographic risks?

At the “Digital Security Starts with Connectivity” tech breakfast on June 11, 2026, Marcin Bała, CTO at Salumanus, addressed these questions in his presentation, “From Dark Fiber to Quantum Security: How to Build Cost-Effective and Post-Quantum-Resilient Transmission Between Data Centers.” His main point was simple: the cost and security of transmission converge at the same point—the optical layer.

From an operational perspective, leasing additional fibers or transmission services may seem like a convenient solution. However, problems arise when an organization scales its environment, launches new services, replicates data across locations, expands backup and disaster recovery capabilities, or connects multiple data centers. Then, the cost increases with each new requirement.

From a security perspective, another question arises: What about data that must remain confidential for more than a few years? This applies to trade secrets, regulated data, medical records, keys, certificates, and information subject to compliance requirements, among other things.

Marcin Bała demonstrated that these two challenges can be addressed as a single infrastructure decision: taking greater control over one’s own transmission layer.

Dark fiber itself is a resource. The full potential of the optical infrastructure can only be realized by “lighting” it using DWDM technology.

DWDM enables the transmission of multiple channels over a single fiber. In practice, this means that, rather than leasing additional fibers or bandwidth, an organization can manage its own optical spectrum, scale transmission capacity, and control costs more effectively.

This is particularly important for connections between data centers, where the demand for bandwidth is growing rapidly. DWDM systems allow transmission speeds to be scaled from 10G to 100G, 400G, and up to 800G without replacing the fiber. Additional “colors,” or optical channels, are simply added.

The presentation also demonstrated that an in-house optical layer can provide a relatively quick return on investment. Once this point is reached, the organization not only gains lower costs, but also greater control over the network’s future development.

The next step is transmission security. Marcin Bała emphasized the importance of Layer-1 encryption, which occurs directly at the optical transmission level.

This approach protects data independently of applications and higher network layers. This is particularly important in environments where large volumes of data are transmitted and latency, performance, and transparency for business services are critical.

Therefore, a good optical layer should ensure scalability, cost-effectiveness, the ability to encrypt data, support for various types of services, compatibility with new and older technologies, and readiness for future security mechanisms, including QKD.

One of the most important themes of the presentation was the risk referred to as “harvest now, decrypt later.” This risk stems from the fact that an adversary can intercept encrypted traffic today and store it until technology allows current cryptographic mechanisms to be broken.

Thus, the quantum threat begins much earlier, at the moment the data is intercepted. It begins much earlier—at the moment the data is intercepted.

If information must remain confidential for five, ten, or more years, its protection should be designed now with post-quantum resilience in mind.

Quantum key distribution (QKD) changes the way we think about key exchange security. In classical cryptography, security is based on the assumption that a specific mathematical problem is too difficult to solve. However, quantum computers could undermine this assumption.

QKD relies on a different mechanism. It uses single photons, and any attempt to eavesdrop alters their state. This cannot be done undetected. If interference occurs, both parties can detect it and discard the key.

However, this does not mean that QKD should be implemented everywhere. Rather, Marcin Bała emphasized the need to make an informed choice about which connections require the highest level of protection. Natural candidates include connections between data centers, data replication and backup, transmission of regulated data, and confidential traffic that must be protected for many years.

The presentation showed that the future of transmission security does not have to be an either/or choice between QKD and post-quantum cryptography. In many scenarios, a hybrid model will be the best solution.

PQC can be used where the sensitivity of the data or volume of traffic is moderate. QKD, especially when combined with PQC, makes sense for critical links, very large volumes of data, and highly confidential information.

This approach allows security to be built up gradually. It does not require a revolution across the entire network. Rather, it requires mapping connections, understanding the data confidentiality landscape, and identifying where the risks are greatest.

The most important takeaway from Marcin Bała’s presentation is that cost-effectiveness and post-quantum resilience do not have to be separate projects. They can be elements of a single strategy.

The first step is mapping the links and determining which data must remain confidential for many years. The second step is to take control of the optical layer where TCO justifies it. Third, add QKD to critical links.

By doing so, an organization reduces transmission costs and prepares its infrastructure for future threats. Dark fiber ceases to be merely a passive asset. Instead, it becomes the foundation for scalable, controlled, and secure communication between data centers.

In a world where data is constantly in motion, digital security truly begins with connectivity. A well-designed optical layer can be one of the most important elements of an organization’s overall resilience.